Adjustable shaft stop



Jan. 11, 1949. RTH- 2,459,012

ADJUSTABLE SHAFT STOP Filed Sept. 30, 1947 Zhwentor Y Jag 5.3512 2% Cittorneg Patented Jan. 11, 1949 I y 2,459,012

. PATENT f i Y Y I 't isaoiz v I SHAFT ST-DP Ja ae ial in a s eno to Base el a ss es a amp ation eip ia "Arm ware

App onfientembe 80, 547, vSe a1.. .2- 7.4175

. ?sT-5 -6) 1 j A 2 is YeniiQs la s &9 ad stable s ate it 8. dju tab e-limit n th ut u of e 'e i aha-Whil am lifi by imitipsthe ran e .of mo me o will b d cribe'd as' applied the said shaft 5. t th solu oa'of a rpli eris 'i i he a usta le st p o t in ention a er an operat on o i lus rated, om r s'es a s ation y a m stru k mo o r hs i h t ne u e y hoeqgra h o rom th panel [o th qhass .I ad n o record dealers in .demfj stra ting their wares, the inner end of the shaft 6 and ofi-setfrom the The maximum power output of the vacuum axis of rotation of the said shaft. A helical (inner) spring l0 (see Fig; 2) is Wound counter t here-Wi h- The e slee e he o m of a it t a e io sl Second preferab y h vier, s ins' ut the ed to ti ou put theamp ine prin 10 an thi sleev llisprovided adbi' n1 a i n, aslius abl S pawn he 9 iaeen to i inne end wit an ext a m ('u cdmro 'shfa "The miss les! twllhle'wi for limiting the a e o mo m o the shaft ia ed to e a the haft (6 'so that it r s a n d; 0 1 m,show r t t wwv o hoot s steiis' t at he either ar ina ce s b d 6 b en a ng the st t onary era-". a. he inn reou. e the use of 1 in t r ad ust, prin I9. s se d to th re at ve y ri d sle e o iously ,acce ible that II by Wrapp t M e doi h s d sprin .,,u .jat by una hori perit mim matedat when e, allrrot tes wi h the s rin rincipal object of the present In and the shaft 6. There is an outwardly exate he pro eina e. h r n eel ti n It aths instea o t nearest obi stiens to resent da adiu tspring W nd a oqrrespo eip proi pi I5 on i haft-st ps m re s e imens term: h W s e ia sleeve t. hese proj t on v a' e 'd, t e ily assemb e to f h 14 nd it tm i tee iiae at o h elane i the enera ehar e e c ed and one wh ch may panel 2 nd a w some through the. anel e s; st d' y' nsk led p rs n withou the e u tise 0i sl ei ial tools 'In' order to set the adjustable stop of the invens 'A -io hei and interns obje t f the es nt tion or any m m e e d s d e to mi nvention'is to provide a novel and inexpensive ing'proeedure is recommendedzfw) With the am-' adjustable shaitistop and one which may be applifier turned on, pull off the knob on the volp nata a shaft of standard form and dimene urns-control shaft't and turn the shaft cloclgwise s'ion's without the of tools and without in any full volume i. e; until the inner radial arm I2 on vfay'alteri'ng' the shaft per so] the sleeve H engages the stationary stop 9. The invention Will be described in connection (b) Press against the outer projection 15 on the with the accompanying drawing wherein: I heavy wire sleeve H as if to turn it clockwise. "Fig. l is avie'iv inelevation of a part of a vac- The eraser end of a pencil may be used, in the uumWuh amplifier with the front panel of the interest of convenience, for this purpose. (0)

set partly broken away to reveal the volume con- 40 Whilefimaintaining this *olonkwise pressure on trol shaft and an adjustable stop, within the inthe projection I5g-rasp the end of the shaft 5 vention, for said shaft; Fig 2 is aside elevation, and turn it fully counter-clockwise. The volume iigIs'isafrontelevation and Fig. 4'is a rear eleis, or should benow at the lowest possible for vation of the 'jsha'ft-mounte'd parts of the stop thev maximum obtainable. (01) Release the pressl ioivnin Figflf sure on theprojeoti'on 15. The maximum volume In-Fig. [of the drawing there is shown a vac obtainable is noW at the low limit, as explained uum tube amplifier comprising a chassis i and above. It will undoubtedly be too low for any a control panel'zj the panel being provided with ordinary purposes. (e). To set the stop for a spaced aper ures": and 4 through which a tonehigher limit of maximum volume due to the recontrol shaft 5' and ayolu me-oontrol shaft 6 proproduction not being sufficiently loud, hold the 'e sp t h e ape tur 3 and. 4 a e hait 6 o k ep the rm I: a ainst the stop a) l eal d 1W r mo ble s me! kn bs n gently res the end 1.4 of the light spring ei i fie i y the, kn b 9n the ar e wire in, hr ugh the means n 4 the panel 2. eh h s ontrol s ait ifii ro m oun er-enthuse d re tion for sma f a .9? 8.1 nqiiya edgenera lg Q5 tiQ tQi-fi r vo ut on, order'to release hebiasing w l ckwise abou the said ax an is o a ly force which causes the spring to "grip the shaft. The pressure applied to the said projection I 4 should be just suflicient to permit the shaft 6 to be turned clockwise. (,0 Hold the said springend l4 and turn the shaft 6 clockwise if necessary to achieve a louder volume. (g) When the maximum desired volume is achieved release both the projection I4 and shaft 6. (h) Replace the knob on the shaft 6.

With the operation of the adjustable stop of the invention clearly in mind it will be apparent that the sole purpose of the outer spring or sleeve H is to provide means (i. e. the projection l5) adjacent to the panel opening 4 for holding the inner spring l against the stationary stop 9 while making the counter-clockwise adjustment which is necessary to achieve-a lower volume. Hence this sleeve ll may be omitted whenever accessibility is not a major consideration. If the sleeve H is omitted it is then necessary to hold the inner projection I3 against thestationary arm 9 (as with the fingers of one hand) in order to permit the shaft to be turned in the counterclockwise direction' required to achieve a lowervolume setting. The omission of the sleeve II is deemed to be within thescope of the present invention.

In the embodiment of. the invention that has been selected for purposes of illustration the sleeve ll comprises a relatively strong, non-yieldable spring. This construction was selected because it permits the projections l2 and I thereon to be made integralwith the sleeve and hence dispenses with the soldering or welding operations which might be necessary if the sleeve were to be constituted of sheet metal.

It will now be apparent that the present invention provides asil'nple inexpensive and trouble-free adjustable shaft-stop and one which may be applied to, and adjusted upon, a volumecontrol shaft or the like without the use of tools.

What is claimed is:

1. An adjustable stop-for a shaft having an axis. of rotation, said adjustable stop comprising a stationary arm mounted adjacent to said shaft and ofi-set from the axis of rotation thereof, a helical spring mounted about said axis and normally biased to engage said shaft for rotation therewith, an extending projection effectively connected to said spring in register with said stationary arm, and a second projection on an end of said spring and to which a force may be applied for temporarily relieving its biasing force upon said shaft whereby to permit of relative rotary movement of said shaft with respect to said spring and thereby to alter the extent of the normal movement of said shaft about its axis by limiting the arc of movement of said extending projection with respect to said stationary arm.

2. The invention as set forth in claim 1 and wherein said stationary arm and said extending projection are mounted adjacent to one end of said helical spring and said second projection comprises the opposite end .of said helical spring.

3. An adjustable stop for a shaft having an axis of rotation, said adjustable stop comprising a stationary arm ofiset from shaft, a helical spring mounted about said axis and normally biased to engage said shaft for rotation therewith, a sleeve secured to said spring for rotation therewith and provided on one end with an extending arm for engagement with said stationary arm, an extending projection on theother end of said spring and to which'a force may be applied in a direction counter to that of said biasing force whereby to permit of relative rotary movement of said spring and sleeve with respect to said shaft and thereby to alter the extent of the movement in one direction of said shaft for limiting the arc of movement of said extending sleeve-arm with respect to said stationary arm, and a discrete extending projection on the corresponding end of said sleeve for temporarily holding said sleeve arm against said stationary arm whereby to permit relative movement in the opposite direction of said shaft with respect to said spring and sleeve and thereby to alter the extent of said movement of said shaft by limiting the arc of movement of said sleeve arm in said opposite direction with respect to said sta tionary arm.

4. The invention as set forth in claim 3 and wherein said sleeve comprises a relatively rigid helical spring, and said sleeve arm and said projection thereon comprise the opposite ends of said relatively rigid helical spring.

5. The invention as set forth in claim 3 and wherein said sleeve comprises a relatively rigid helical spring, said sleeve-arm and said projection thereon comprise the opposite ends of said relatively rigid helical spring, and one end of the inner one of said helical springs is wrapped about the extending arm of said outer helical spring.

6. In a vacuum tube amplifier installation having a control panel and a volume-control shaft which extends through an aperture in said front panel, said aperture being normally concealed by a removable knob on the free-end of said shaft; an adjustable stop for limiting the arc of movement of said shaft and hence the output of said amplifier, said adjustable stop comprising, a stationary arm mounted adjacent to the inner end of said shaft and off-set from the axis of rotation thereof, a helical spring mounted about said axis and normally biased to engage said shaft for rotation with said shaft, a sleeve mounted on said spring for rotation therewith and provided adjacent to its inner end with an extending arm for limiting the arc of movement of said shaft by engagement with said stationary arm, an extending projection on the outer end of said spring and accessible through said panel opening for temporarily relieving the biasing force applied to said shaft whereby to permit of relative rotary movement, in one direction, of said shaft with respect to said spring and said sleeve and thereby to alter the extent of the movement in said direction of said shaft by limiting the arc of movement of said extending sleeve-arm with respect tosaid stationary arm, and a discrete extending projection on the outer end of said sleeve and accessible through said panel opening for temporarily holding said inner arm against said stationary arm whereby to permit relative movement in the opposite direction of said shaft with respect to said spring and sleeve and thereby to alter the extent of said movement of said shaft by limiting the arc of movement of said inner sleeve-arm, in said opposite direction, with respect to said stationary arm.

a '7. In a vacuum tube amplifier installation having a control panel and a volume-control shaft which extends through an aperture in said front panel, said aperture being normally concealed by a removable knob on the free-end of said shaft; an adjustable stop for limiting the arc of movement of said shaft and hence the output of said amplifier, said adjustable stop comprising: a stationary arm mounted adjacent to the inner end of said shaft and off-set from the axis of rotation thereof, a helical spring wound counterclockwise about said axis and normally biased to engage said shaft for rotation therewith, a sleeve mounted on said spring for rotation with said shaft and provided adjacent to its inner end with an extending arm for limiting the arc of movement of said shaft by engagement with said stationary arm, an extending projection on the outer end of said spring adjacent to said panel opening and to which a counter clockwise force may be applied for temporarily relieving the biasing force applied to said shaft whereby to permit of relative rotary movement, in the clockwise direction, of said shaft with respect to said spring and said sleeve and thereby to alter the extent of the movement in the clockwise direction of said shaft by limiting the arc of movement of said extending sleeve-arm with respect to said stationary arm, and a discrete extending projection on the outer end of said sleeve and accessible through said panel opening for temporarily holding said inner arm against saidstationary arm whereby to permit relative counter-clockwise movement of said shaft with respect to said spring; and sleeve and thereby to alter the extent.

REFERENCES CITED The following references are of record in the file-of this patent:

UNITED STATES PATENTS Number; Name Date 1,598,182 White et al Aug. 31, 1926 1 ,940,130 Howell Dec. 19, 1933 2,169,321 Jones Aug; 15, 1939 2,220,599 Galter Nov. 5, 1940 

